John J Benevelli

US Patent:

52264726, Jul 13, 1993

Filed:

Nov 15, 1991

Appl. No.:

7/792705

Inventors:

John A. Benevelli - Burbank IL
Michael L. Murray - Franklin Park IL
Duane C. Drinkwine - Berwyn IL

Assignee:

Lab-Line Instruments, Inc. - Melrose Park IL

International Classification:

F25B 2900

US Classification:

165 30

Abstract:

A temperature-controlled environmental chamber includes a resistance heater controlled by a solid state relay and a refrigeration unit including an electronically controlled suction throttling valve connected in the refrigerant line between the evaporator and the inlet of the compressor. A temperature controller senses the temperature in the chamber and compares it to a set point temperature and outputs a pulse-width modulated control signal indicative of the difference between the two temperatures. The control signal directly controls the heater relay for substantially continuous variation between minimum and maximum heating conditions. The control signal is converted to an analog signal for controlling the throttling valve of the refrigeration unit for substantially continuous variation between maximum and minimum cooling conditions, so that the amount of cooling provided is inversely proportional to the amount of heating provided. A hot gas bypass is provided for maintaining a minimum input pressure on the condenser and a refrigerant bypass is provided to maintain the input temperature of the compressor below a predetermined maximum.

US Patent:

52479897, Sep 28, 1993

Filed:

Feb 26, 1992

Appl. No.:

7/841552

Inventors:

John A. Benevelli - Burbank IL

Assignee:

Lab-Line Instruments, Inc. - Melrose Park IL

International Classification:

F25B 2900

US Classification:

165 30

Abstract:

A temperature-controlled environmental chamber includes a resistance heater powered through a first solid state relay and a refrigeration unit including an electrically powered thermally controlled suction throttling valve connected in the refrigerant line between the evaporator and the inlet of the compressor, and including a bimetal motor and a heating element therefor powered through a second solid state relay. A thermostat senses the temperature in the chamber and compares it to a set point temperature and outputs a pulse-width modulated control signal indicative of the difference between the two temperatures. The control signal directly controls the heater relay for substantially continuous variation of the heater between minimum and maximum heating conditions. The control signal also directly controls the throttling valve relay by controlling the power to its heating element for substantially continuous variation of the valve between maximum and minimum cooling conditions, so that the amount of cooling provided is inversely proportional to the amount of heating provided.